X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from zproxy.gmail.com ([64.233.162.203] verified) by logan.com (CommuniGate Pro SMTP 4.3.5) with ESMTP id 1021786 for flyrotary@lancaironline.net; Sat, 25 Jun 2005 23:13:34 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.162.203; envelope-from=wdleonard@gmail.com Received: by zproxy.gmail.com with SMTP id 13so84172nzn for ; Sat, 25 Jun 2005 20:12:49 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:reply-to:to:subject:in-reply-to:mime-version:content-type:references; b=lLBHj2cvXhKP3YEe7n2+KhZj1v9C2ibLzAaedVKLAEXixXUGNn8hcc0LWi9A6vub3aVCzdcGHJh7v4Xq5v4P1KOLqMJ+xrvvjy2LLfq9ewJx0z/wn2RFJJGcNZWOts8rUBQ/ht2+Dm0FVViECU7c6oTwePzphZAavhtNmOCJTr4= Received: by 10.36.65.19 with SMTP id n19mr3422123nza; Sat, 25 Jun 2005 20:12:49 -0700 (PDT) Received: by 10.36.9.4 with HTTP; Sat, 25 Jun 2005 20:12:49 -0700 (PDT) Message-ID: <1c23473f0506252012c7f90a8@mail.gmail.com> Date: Sat, 25 Jun 2005 20:12:49 -0700 From: David Leonard Reply-To: David Leonard To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Coolant Leak In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_2845_21099198.1119755569372" References: ------=_Part_2845_21099198.1119755569372 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Ok, here is my guess: On 6/25/05, John Slade wrote:=20 >=20 > OK, Dave. If that makes sense, explain this.... :) > After start-up - 29 psi (24 psi cap) >=20 coolant is expanding rapidly. The pressure rating of most caps is a rough= =20 estimate at best. It is determined by the metal spring. That metal spring= =20 will also change the force it applies based on it's temperature (though I a= m=20 not sure which direction and how much). Run-up 25 PSI >=20 Coolant is still expanding though possibly at a slower rate and/or the=20 spring is now also warm and exerting less force. Two trips around the pattern - zero PSI the entire time >=20 Now you are getting good air flow after climb out and the temp drops a=20 little from its peak value, so the volume of coolant contracts and sucks a= =20 little back in from the overflow - zero psi. third downwind - 8 PSI. >=20 Now you have reached steady state temperature, or perhaps a second slight= =20 rise in temp as the overall under cowl temp rises (all heat sinks under the= =20 cowl become saturated with heat). Also, there is continuous vaporization of= =20 the coolant, which rapidly re condenses after leaving the hottest areas. Th= e=20 amount of this vaporization is a function of the pressure and temp. So it= =20 will seek some equilibrium at a pressure that is greater than zero. ie. mor= e=20 vaporization increases the pressure, which in turn limits amount of=20 vaporization. taxi back to hangar - 10 PSI. >=20 Perhaps slightly warmer now (especially in those backward flying airplanes= )=20 and the vaporization:pressure equilibrium has shifted a little. After cool down - coolant still full to the brim. >=20 Yea, no reason for me to think you have a leak. (I can convince myself of= =20 anything :-) --=20 Dave Leonard Turbo Rotary RV-6 N4VY http://members.aol.com/_ht_a/rotaryroster/index.html http://members.aol.com/vp4skydoc/index.html ------=_Part_2845_21099198.1119755569372 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Ok, here is my guess:

On 6/25/05, = John Slade <sladerj@bellsou= th.net> wrote:
OK, Dave. If t= hat makes sense, explain this.... :)
  &n= bsp; After start-up - 29 psi (24 psi cap)
 
coolant is expanding rapidly.  The pressure rating of most caps i= s a rough estimate at best.  It is determined by the metal s= pring.  That metal spring will also change the force it applies based = on it's temperature (though I am not sure which direction and how much).

  &n= bsp; Run-up  25 PSI
 
Coolant is still expanding though possibly at a slower rate and/or the= spring is now also warm and exerting less force.

  &n= bsp; Two trips around the pattern - zero PSI the entire time<= /div>
 
Now you are getting good air flow after climb out and the temp drops a= little from its peak value, so the volume of coolant contracts and sucks a= little back in from the overflow - zero psi.

  &n= bsp; third downwind - 8 PSI.
 
Now you have reached steady state temperature, or perhaps a second sli= ght rise in temp as the overall under cowl temp rises (all heat sinks under= the cowl become saturated with heat).   Also, there is cont= inuous vaporization of the coolant, which rapidly re condenses after leavin= g the hottest areas. The amount of this vaporization is a function of the p= ressure and temp.  So it will seek some equilibrium at a pressure that= is greater than zero.  ie. more vaporization increases the pressure, = which in turn limits amount of vaporization.

  &n= bsp; taxi back to hangar - 10 PSI.
 
Perhaps slightly warmer now (especially in those backward flying airpl= anes) and the vaporization:pressure equilibrium has shifted a little.
=
  &n= bsp; After cool down - coolant still full to the brim.
<= /blockquote>
 
Yea, no reason for me to think you have a leak.   (I can con= vince myself of anything  :-)
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